Supplementing human and animal diets with essential amino acids and/or other bioactive agents improves health and performance. Bioactives may be sensitive to degradation, yet need to be provided with a particular release profile. Combining the bioactive in a particular matrix composition or with a layer coating composition comprising a polymer is one way to deliver protected bioactives with a desired release profile. Providing amino acids and/or bioactive agents to ruminants, in particular, is challenging because microbes in the rumen may digest and degrade the bioactive agent of interest before it can be absorbed and utilized by the animal. Over the years, various protection approaches have been taken, but with mixed results. What is needed, therefore, is an improved means for protecting bioactive agents. In particular, compositions that provide pH-dependent release provide advantages in the delivery of bioactives.